20230095 Ver 1_More Info Received_20230227

Northwest
Geoocience
Pc
February 27, 2023
US Army Corps of Engineers
Wilmington District
Raleigh Regulatory Field Office
3331 Heritage Trade Drive
Suite 105
Wake Forest, NC 27857
Via Electronic Mail: [e-mail]
Attention: Mr. David Bailey, PWS
Subject: Stabilization of Petree Creek
Winston-Salem
Response to February 14, 2023 email
Dear Mr. Bailey:
P.O. Box 0415
High Point, NC 27202
33E-555-4351
Fax [phone]
This letter is in response to your February 14, 2023 email concerning the submittal of
plans and specifications and a PCN for this project (SAW-2023-00159). Based on your
email and our telephone conversation, Northwest Geoscience, PC (NWGS) make the
following responses:
1. The request for coverage under NWP 27 was based on discussions with Jean
Gibby and others at the USACE. We agree that the NWP 13 is more applicable
and have no concerns with this permit. Therefore, we request that the
application be revised for coverage under NWP 13.
2. The first task to be implemented will be to cut the new channel as shown on
the plans. This will divert the stream from the area where the retaining wall
will be constructed. If groundwater is encountered in the excavation for the
footings, this water will be pumped out using trash pumps.
3. The planned low water channel which will be constructed lies well within the
outer stream banks. The current low water channel consists of sand and
gravel. Because the new low water channel will be constructed through a
large gravel and sand bar, it is not anticipated that any vegetation could be
expected to survive. Therefore, we do not plan to plant along this reach of the
channel.
4. We agree that there will be a reduction of stream channel length from go to
62 linear feet. The 90 feet is due to the large meander that has formed and
caused the erosion that is threatening to undermine the bank at the town
house. The new stream channel restores the original thalweg. We believe that
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there is no other alternative. It was initially proposed to push the new
channel further to the opposite bank with a large meander. However, this was
not chosen as a possible stream channel path as it would create a high velocity
bend on the opposite bank and could result in the same problem currently
being experienced only on the opposite bank. This would then create the
potential for undermining of the townhouses on the other side of Petree
Creek. Finally, the length of the new channel just does not allow for natural
design techniques. The length of the thalweg and the difference in elevations
between the upstream and downstream points where the new channel will
divert from the existing channel and intersect with the lower potion of the
natural channel are simply too limited to allow for natural design techniques.
NWGS is of the opinion that even with the net loss of 28 feet of the stream,
the proposed stream course is the only viable solution given the site
conditions.
We hope that this response is sufficient to move this project forward. We are copying
the NC Department of Water Resources with this letter. Should you have additional
questions, please do not hesitate to contact NWGS.
Sincerely,
Northwest Geoscience, PC
AlanVary �NeAnLG
President
cc: Seren M. Homer seren.homerPncdenr.gov
Rebecca D. Chandler rebecca.chandler Pncdenr.gov